1. Field of the Invention
The present invention relates to an automobile drive recorder adapted to continuously take an image of a scene around an automobile by using a monitoring camera installed in the automobile, and, if a detection signal indicating an occurrence of an abnormal driving state is output by an abnormal state detection sensor, record image data of the scene for a period with a particular length around the time of the occurrence of the abnormal driving state, together with additional information associated with the driving state, into a record memory as drive record data.
2. Description of the Related Art
Japanese Unexamined Patent Application Publication No. 2000-6854 discloses an automobile drive recorder adapted to record image information output by a CCD camera and sensor information output by various kinds of sensors such as a speed sensor and an acceleration sensor into a random access memory while updating the data stored in the random access memory as required. If a shock sensor detects a shock to a driver's automobile, information recorded in the memory is transferred to a flash memory and further output via an encoder from an output terminal so that the information is played back. This allows it to store an image and sensor information for a period immediately before an occurrence of an accident and thus allows it to analyze a state in which the accident occurred. Japanese Unexamined Patent Application Publication No. 2003-203285 discloses a state recording apparatus including initial state recording means for recording a result of a test performed before a driving of an automobile is started, running state recording means for recording a running state of the automobile while updating the recorded data as required, accident detection means for detecting an occurrence of an accident by using a shock sensor, and accident state recording means for recording a state of the accident of the automobile. This state recording apparatus makes it possible to, if an accident occurs, determine the cause of the accident by analyzing recorded information indicating whether the automobile had a failure, the GPS information, and sound information captured via a microphone. Japanese Unexamined Patent Application Publication No. 2005-57661 discloses an accident recording system adapted to take an image of an outside scene and an image of the inside of an automobile when the automobile is being driven, capture a voice/sound in the inside of the automobile via a microphone, and transmit the image data and the voice/sound data to a recording server via a network. If an occurrence of an accident is detected by a shock sensor, recording of the data is continuously performed regardless of the driving state.
Japanese Unexamined Patent Application Publication No. 2001-63500 discloses an obstacle detection apparatus adapted to, instead of detecting a shock that an automobile receives, detect an approaching obstacle using an ultrasonic sensor and display an image of the obstacle approaching the automobile on a display screen to inform a driver of the presence of the approaching obstacle. Japanese Unexamined Patent Application Publication No. 11-183613 discloses an automobile radar apparatus that transmits a frequency-modulated radio wave signal and detects the distance to a target or the relative speed between an automobile and the target based on a signal reflected from the target.
However, in the techniques disclosed in Japanese Unexamined Patent Application Publication No. 2000-6854, Japanese Unexamined Patent Application Publication No. 2003-203285, and Japanese Unexamined Patent Application Publication No. 2005-57661, an image of an accident is recorded when some shock caused by the accident is actually detected, and thus it is difficult to record an image of an accident with a bicycle, a motorcycle, or a pedestrian or a small accident with another automobile, which does not impose a considerable shock on the automobile. Besides, in these techniques, an image of a dangerous state/situation that may result in an accident is not recorded, unless the dangerous state/situation actually results in an actual accident. Furthermore, it is impossible to analyze a usual driving state/condition to manage the driving state/condition of a driver.
On the other hand, in the technique disclosed in Japanese Unexamined Patent Application Publication No. 2001-63500 in which an ultrasonic sensor is used instead of a shock sensor, although it is possible to record an image of a state/situation that can cause an accident even when the state/situation does not result in an actual accident, an attenuation of an ultrasonic wave caused by rain or noise generated by a driver's automobile can cause a reduction in detection reliability. Another problem of this technique is that it takes a processing time to detect the distance and thus it is difficult to detect a target at a very close position. The radio wave radar disclosed in Japanese Unexamined Patent Application Publication No. 11-183613 also has a problem with detection of a target at a close position. Another problem of this technique is that a complicated circuit is needed.